Since Kant, liberal scholars of international relations have hypothesized that greater cross-border contact can be a powerful force for good. The idea is that such contact encourages a sense of shared international community, breaking down artificial barriers separating people into different nations and inhibiting their natural human affinities for one another. This intuitively appealing hypothesis has inspired several famous student exchange programs, which among other potential positive effects are expected to quell nationalist fervors and ward off international conflict.

Despite its ubiquity, this hypothesis has rarely been tested in a rigorous way. Does cross-border contact really foster a feeling of community? In a recent study, I used a natural experiment across a sample of American “study abroad” students at 11 colleges in New England, the Midwest and the South to carry out a unique test. The institutional structure of study abroad makes it well-suited for a natural experiment. Students are typically placed in foreign settings for either the fall or spring semester, with the winter break providing a valuable window during which a treatment group of students just returning from a semester abroad can be compared with a control group of students who are about to embark. Since all subjects are predisposed to participate, the design controls for self-selection, and the choice of which semester is a logistical one with no obvious implications. These are significant design improvements over earlier studies that did not control for self-selection or lacked a strong control group.

More than 500 students were surveyed on their feelings of international community, perceptions of foreign threat, and levels of nationalism and patriotism, as well as demographics and study abroad program characteristics. As expected, those returning from a semester abroad (the treatment group) were not significantly different either demographically or in terms of program choices from those about to take their semester abroad (the control group). For instance, they selected the same host countries in which to study abroad, especially Spain, France, Italy and the United Kingdom, and females outnumbered males in both groups. All this mirrors the general population of American study abroad students, who are majority female and tend to study abroad most in Western Europe.

First, I tested the core liberal hypothesis that cross-border contact promotes a sense of shared international community, or what political scientist Karl Deutsch called a “we-feeling” across cultural divides. Theorists define this in terms of warmth, shared understandings and values, and trust. Surprisingly, the hypothesis was not supported: None of the indicators for international community was higher on average for students returning from study abroad than for those yet to travel. In fact, those who had just returned from a semester abroad felt they had significantly fewer values in common and were more likely to say their understandings of key concepts were different from the people of their host country. None of this was sensitive to potential moderators like whether or not students opted to live with a host family. Given the intuitive plausibility of the liberal hypothesis, these results are striking.

How about threat perceptions? I asked students to rate how threatening they would consider their study abroad host country if it were to surpass the United States in terms of material power, such as economic growth or military expansion. In theory, cross-border contact should mitigate . . . .